Four stem fractures in a 12-year follow-up study of 9,135 patients with Exeter hip stems at seven teaching facilities in Japan.

BACKGROUND: Although excellent long-term results have been reported for the Exeter stem, stem fracture is recognized as a rare complication. However, there have been no reports on the incidence and risk factors for stem fractures based on detailed population information. This study aimed to clarify the incidence of Exeter hip stem fracture based on detailed population information from seven Exeter stem teaching centers in Japan and to examine the risk factors for stem fracture. METHODS: A total of 8,499 primary total hip arthroplasties (THA) and 636 revision hip arthroplasties (revisions) performed at seven Exeter teaching hospitals between 1999 and 2021 were included and retrospectively investigated based on medical records. RESULTS: Stem fractures were identified in two primary THA (fracture rate: 0.02%) and two revision THA (fracture rate: 0.21%) cases. The stem length was ≤125 mm in three out of these four cases. Revision and 30 stem were the risk factors for stem fractures. Weight and body mass index (BMI) were not significantly associated with the occurrence of stem fractures. CONCLUSIONS: In Western countries, the incidence of Exeter stem fractures is reportedly 0.017-0.15% for primary THA and 0.99-1.21% for revision THA. In this study, the incidence of primary THA was 0.02%, which is similar to the lowest reported rate, whereas the incidence of revision THA was 0.21%, which is lower than that reported in previous studies. Revision surgery had the same risk factors as those reported in the West-namely, stem length ≤125 mm (except for the 30 stem) and BMI, which were not risk factors in Japanese patients.

A case of acute septic arthritis of the hip joint caused by Panton-Valentine leukocidin-positive ST772 community-acquired methicillin-resistant Staphylococcus aureus.

Acute septic arthritis (ASA) caused by Staphylococcus aureus can lead to fulminant arthritis and cause permanent joint destruction. In particular, infection caused by methicillin-resistant Staphylococcus aureus (MRSA) becomes intractable and severe owing to limitation of therapeutic drugs. Here, we report the case of a young patient with ASA without any record of overseas travel, who was infected by the Panton-Valentine leukocidin-positive Bengal-Bay clone, which is a predominant community-acquired MRSA in India.

Pain Catastrophizing Is Independently Associated with Quality of Life in Patients with Severe Hip Osteoarthritis.

OBJECTIVE: Pain catastrophizing is an important pain-related variable, but its impact on patients with osteoarthritis is uncertain. The aim of the current study was to determine whether pain catastrophizing was independently associated with quality of life (QOL) in patients with osteoarthritis of the hip. DESIGN: Cross-sectional study conducted between June 2017 and February 2018. SETTING: Tertiary center. SUBJECTS: Seventy consecutively enrolled patients with severe hip osteoarthritis who had experienced pain for six or more months that limited daily function, and who were scheduled for primary unilateral total hip arthroplasty. METHODS: QOL was measured using the EuroQOL-5 Dimensions questionnaire, the Japanese Orthopedic Association Hip Disease Evaluation Questionnaire, and a dissatisfaction visual analog scale. Covariates included pain intensity, pain catastrophizing, range of hip motion, and gait speed. The variables were subjected to multivariate analysis with each QOL scale. RESULTS: The median age was 68 years, and the median Pain Catastrophizing Scale score was 26. In multiple regression analysis, pain catastrophizing, pain intensity in both hips, pain intensity on the affected side, hip flexion on the affected side, and gait speed were independently correlated with QOL. CONCLUSIONS: Pain catastrophizing was independently associated with each QOL scale in preoperative patients with severe hip osteoarthritis. Pain catastrophizing had either the strongest or second strongest effect on QOL, followed by pain intensity.

Urinary ß-2 Microglobulin Levels Sensitively Altered in an Osteomalacia Patient Receiving Add-on Adefovir Dipivoxil Therapy for Hepatitis B Virus Infection.

Adefovir dipivoxil (ADV) is effective for hepatitis B virus (HBV) infection; however, ADV may provoke renal injury resulting in osteomalacia, and this side effect is seldom recognized until bone fractures emerge. We herein present a 66-year-old woman with HBV infection who received ADV for 6 years. Although she exhibited no sign of bone fractures, her urinary ß-2 microglobulin (ß2MG) level increased to 83,837 µg/L and scintigraphy revealed minimal fractures of the third rib. ADV was subsequently reduced and her urinary ß2MG rapidly fell to 3,637 µg/L. Conversely, her urinary N-acetyl-ß-D-glucosaminidase, and serum phosphate, alkaline phosphatase levels did not respond.

Can larger-bodied cemented femoral components reduce periprosthetic fractures? A biomechanical study.

INTRODUCTION: The risk for late periprosthetic femoral fractures is higher in patients treated for a neck of femur fracture compared to osteoarthritis. It has been hypothesised that osteopaenia and consequent decreased stiffness of the proximal femur are responsible for this. We investigated whether a femoral component with a bigger body would increase the torque to failure in a biaxially loaded composite Sawbone model. MATERIALS AND METHODS: A biomechanical bone analogue was used. Two different body sizes (Exeter 44-1 versus 44-4) of a polished tapered cemented femoral stem were implanted by an experienced surgeon in seven bone analogues each and internally rotated at 40°/s until failure. Torque to fracture and fracture energy were measured using a biaxial materials testing device (Instron 8874, MI, USA). The data were non-parametric and therefore tested with the Mann-Whitney U test. RESULTS: The median torque to fracture was 156.7 Nm (IQR 19.7) for the 44-1 stem and 237.1 Nm (IQR 52.9) for the 44-4 stem (p = 0.001). The median fracture energy was 8.5 J (IQR 7.3) for the 44-1 stem and 19.5 J (IQR 8.8) for the 44-4 stem (p = 0.014). CONCLUSION: The use of large body polished tapered cemented stems for neck of femur fractures increases the torque to failure in a biomechanical model and therefore is likely to reduce late periprosthetic fracture risk in this vulnerable cohort.

Comparison of two pressurisers for cementation of the proximal femur.

PURPOSE: To compare pressures generated by 2 different cement pressurisers at various locations in the proximal femur. METHODS: Two groups of 5 synthetic femurs were used, and 6 pressure sensors were placed in the femur at 20-mm intervals proximally to distally. Cement was filled into the femoral canal retrogradely using a cement gun with either the half-moon pressuriser or the femoral canal pressuriser. Maximum pressures and pressure time integrals (cumulative pressure over time) of the 2 pressurisers were compared. RESULTS: At all sensors, the half-moon pressuriser produced higher maximum pressures and pressure time integrals than the femoral canal pressuriser, but the difference was significant only at sensor 1 (proximal femur). This may result in reduced cement interdigitation in the proximal femur. CONCLUSION: The half-moon pressuriser produced higher maximum cementation pressures and pressure time integrals than the femoral canal pressuriser in the proximal femur region, which is critical for rotational stability of the implant and prevention of implant fracture.

Periprosthetic fracture torque for short versus standard cemented hip stems: an experimental in vitro study.

In an attempt to preserve proximal femoral bone stock and achieve a better fit in smaller femora, especially in the Asian population, several new shorter stem designs have become available. We investigated the torque to periprosthetic femoral fracture of the Exeter short stem compared with the conventional length Exeter stem in a Sawbone model. Forty-two stems; 21 shorter and 21 conventional stems both with three different offsets were cemented in a composite Sawbone model and torqued to fracture. Results showed that Sawbone femurs break at a statistically significantly lower torque to failure with a shorter compared to conventional-length Exeter stem of the same offset. Both standard and short-stem designs are safe to use as the torque to failure is 7-10 times that seen in activities of daily living.

Outcomes of Charnley total hip arthroplasty using improved cementing with so-called second- and third-generation techniques.

BACKGROUND: Techniques of cemented total hip arthroplasty have developed over time. We present the outcomes of Charnley total hip arthroplasty performed using improved second- and third-generation cementing techniques. METHODS: We reviewed the radiologic results of 91 Charnley total hip arthroplasties performed using second- and third-generation cementing techniques. Second-generation techniques involved making multiple anchor holes, a double-cementing method on the acetabular side and an intramedullary plug, and retrograde filling with a cement gun on the femoral side in 57 hips. Third-generation techniques involved additional vacuum mixing and cement pressurization in 34 hips. RESULTS: Joint survival rates at 20 years when using second-generation techniques were 89% for the socket and 94% for the stem with aseptic loosening as the end point; the survival rates at 10 years when using third-generation techniques were 97 and 100%, respectively. According to our radiographic evaluation system for the clear zone at 5 years, there was less clear zone in the acetabular side with the third-generation techniques than with second-generation techniques. In the femoral side, there was very little development of the clear zone, but the difference between generations was not significant. CONCLUSIONS: Second- and third-generation cementing techniques showed excellent survivorship. The clear zone scores at 5 years indicated that third-generation techniques were effective, especially in the acetabular side, and may produce better long-term results than second-generation techniques.

Long-term outcomes of shelf acetabuloplasty for developmental dysplasia of the hip in adults: a minimum 20-year follow-up study.

BACKGROUND: Shelf acetabuloplasty has been applied to secondary osteoarthritis of the hip due to congenital dislocation or acetabular dysplasia; however, there are few reports on the long-term outcomes of this operation. Here, we aimed to investigate the long-term effects of our shelf acetabuloplasty for developmental dysplasia of the hip in adults. METHODS: Outcomes for 28 hips (7 with pre-arthrosis, 21 with initial stage of arthrosis) were retrospectively reviewed clinically and radiologically at a minimum of 20 years after operation. Mean age of the patients at operation was 34 years (range 17-54 years), and the mean follow-up period was 25 years (range 20-32 years). RESULTS: Mean Japanese Orthopaedic Association hip score improved from 76 points preoperatively to 82 points, and mean pain score improved from 24 points preoperatively to 33 points at 20 years. Mean Sharp angle improved from 51° preoperatively to 37° immediately after the operation. Similarly, the mean center-edge angle improved from -4° to 38°, and the mean acetabulum head index improved from 52 to 99%. More than 50% of the hips showed no change in joint space width at 20 years. Survival rates were 100% at 10 years, 93% at 20 years and 71% at 32 years, with conversion to total hip replacement as the endpoint. CONCLUSION: Long-term outcomes of our shelf acetabuloplasty were comparable to other reports, and the clinical outcomes and survivorship revealed positive long-term effects of our procedure over approximately 20 years.

A novel technique for impaction bone grafting in acetabular reconstruction of revision total hip arthroplasty using an ex vivo compaction device.

BACKGROUND: Impaction bone grafting allows restoration of the acetabular bone stock in revision hip arthroplasty. The success of this technique depends largely on achieving adequate initial stability of the component. To obtain well-compacted, well-graded allograft aggregates, we developed an ex vivo compaction device to apply it in revision total hip arthroplasty on the acetabular side, and characterized mechanical properties and putative osteoconductivity of allograft aggregates. METHODS: Morselized allograft bone chips were compacted ex vivo using the creep technique and subsequent impaction technique to form the bone aggregates. Impaction allograft reconstruction of the acetabulum using an ex vivo compaction device was performed on eight hips. The mechanical properties and three-dimensional micro-CT-based structural characteristics of the bone aggregates were investigated. RESULTS: In clinical practice, this technique offered good reproducibility in reconstructing the cavity and the segmental defects of the acetabulum, with no migration and no loosening of the component. In vitro analysis showed that the aggregates generated from 25 g fresh-frozen bone chips gained compression stiffness of 13.5-15.4 MPa under uniaxial consolidation strain. The recoil of the aggregates after compaction was 2.6-3.9%. The compression stiffness and the recoil did not differ significantly from those measured using a variety of proportions of large- and small-sized bone chips. Micro-CT-based structural analysis revealed average pore sizes of 268-299 µm and average throat diameter of pores in the bone aggregates of more than 100 µm. These sizes are desirable for osteoconduction, although large interconnected pores of more than 500 µm were detectable in association with the proportion of large-sized bone chips. Cement penetration into the aggregates was related to the proportion of large-sized bone chips. CONCLUSION: This study introduces the value of an ex vivo compaction device in bone graft compaction in clinical applications. In vitro analysis provided evidence that compaction of sequential layers of well-compacted, well-graded bone aggregates, i.e., the aggregates comprising smaller sized chips at the host bone side and larger sized chips at the component side, may have the advantages of initial stability of the acetabular component and biological response of the grafted aggregates.